How a Country Becomes a Member of the European Union

Joining the European Union is rarely quick. It is one of the most demanding processes in international affairs — a years-long negotiation in which an applicant country must reshape large parts of its laws and institutions to match the rules already shared by the existing members. The path is well defined, but it is long, and at several points any single member state can slow it down or stop it.

Here is how that path works, from first application to full membership.

Who is eligible, and the values test

The legal starting point is the EU’s founding treaties. Under Article 49 of the Treaty on European Union, membership is open to any European state that respects the Union’s core values and is committed to promoting them. Those values, set out in Article 2, include respect for human dignity, freedom, democracy, equality, the rule of law and human rights.

Eligibility is then made concrete by the Copenhagen criteria, agreed at a European Council meeting in Copenhagen in 1993. A candidate must demonstrate three things:

• Stable institutions guaranteeing democracy, the rule of law, human rights, and respect for and protection of minorities.
• A functioning market economy able to cope with competitive pressure within the Union.
• The ability to take on the obligations of membership, including the aims of political, economic and monetary union.

Later European Council meetings reinforced these conditions and added an expectation that candidates resolve outstanding border disputes with their neighbours before joining.

The three main stages

The process, formally called accession, moves through three broad stages: becoming a candidate, negotiating the terms, and ratifying a treaty.

Before any of this, a country aspiring to join usually first signs an association agreement, which helps prepare it for candidacy. When it formally applies, candidate status is granted by a unanimous decision of the European Council, acting on a recommendation from the European Commission. Unanimity matters here: every existing member must agree.

The longest stage: negotiating the acquis

The heart of the process is the accession negotiation, and it is by far the longest stage. What the candidate must adopt is the acquis — the entire accumulated body of EU law, an enormous collection of rules running to roughly 130,000 pages.

To make this manageable, the acquis is divided into 35 chapters, each covering a policy area such as taxation, the environment, the free movement of goods, or justice and home affairs. The number of chapters has changed over the years; earlier enlargements used fewer.

A crucial and often misunderstood point is that the rules themselves are not up for negotiation. A candidate cannot bargain away EU law it dislikes. The acquis must be adopted in full. What is actually negotiated is the practical question of how and when the country will implement and enforce each chapter — including, in some cases, temporary transition periods agreed by either side.

The candidate does not negotiate the rules. It negotiates the timetable and the proof that it can apply them.

How the chapters are worked through

The process begins with screening, a detailed assessment of how prepared the candidate is in each of the 35 chapters. Chapters are then opened for negotiation and, once the EU is satisfied that a chapter has been implemented sufficiently, closed. A closed chapter can be reopened if the Commission concludes the country has slipped out of compliance.

Under the EU’s more recent approach, the chapters dealing with the rule of law, justice and fundamental rights are given special weight. They are opened early and kept open throughout, on the reasoning that democratic and legal reforms take time and underpin everything else. If progress on these falls behind, it can hold up the rest of the negotiation.

Throughout, the Commission publishes regular progress reports tracking how the candidate is doing.

The final step: signing and ratification

Negotiations formally conclude only when all 35 chapters have been closed. At that point an accession treaty is drawn up between the candidate and the EU.

The approvals required for the treaty are substantial. The European Parliament must give its consent, and the European Council must agree unanimously. The treaty is then signed and must be ratified — both by the acceding country and by every existing member state, typically through their national parliaments. Only once that ratification is complete, on the agreed accession date, does the country become a full member of the Union.

How long it takes, and what’s happening now

There is no fixed timetable, and the duration varies widely with a country’s starting point and the political climate. The Pew Research Center has noted that, on average, accession has taken roughly nine years for the members that joined through this process, with some cases stretching considerably longer. Several countries are currently at different stages of accession negotiations, including in the Western Balkans and, more recently, Moldova and Ukraine.

One feature of the current era is worth noting. Unlike some earlier enlargements, today’s negotiations are open-ended: opening talks carries no guarantee of eventual membership. A country must earn its place chapter by chapter — and the existing members must, at every key juncture, agree to let it in.